Trying to solve a persistent cel 41no hego sensor code, decided to check plugs/cables etc while I'm at it, since at times it felt like the truck was missing or spluttering (very slight, but I'm used to a 4 cyl on an 8 I guess it's a little more subtle)

Remove #1 wire, and a lump of whitish/light brown soft material drops from the boot. It's soft and ashy and breaks straight up. There's a bit of it on the terminal in the distributor too.....cables/cap are bosch plugs are NGK looks like platinums, they have the pointy tip (never seen them before at first I thought it was one eroded plug!)

Cables and plugs and cap were replaced in 2006 and I doubt I've done more than 30,000km so not a great deal of driving but all city, short trips pretty much. I know I could just replace them to be safe and know they were new, but I pretty much live from (small) paycheck to paycheck, and my wife's on school hols so no pay til september so I'm trying not to go overboard (and I've seen posts from people with same issue as mine and they've replaced almost everything to find out their cats are bad so I'm trying to test, rather than just replace.

One of my manuals says to test for resistance in the cable, no more than 5 k/ohms per foot, and to test from inside the cap, through to plug boot. Testing the # 1 cable, just over a foot end to end, not in the dist cap, I get about 3k ohm. (regular multimeter not an auto one, I do have an older autotuneup meter, if there's a question of impedence, should I be using a proper auto tester?) If I test from plug boot to inside contact on dist cap I get o/l as in out of range message....

Plug looks good, no issues. Clean, no bad deposits. If wire was bad, plug would look bad?

Decide to test cable # 2 whose plug also appears good. Same measurement with regular multimeter. Find it hard to believe both bad, when both plugs clean. Truck mostly lacked power and had the ceo was not running rough (but like I said seemed to jerk or hesitate slightly at the top end while this issue was happening)

I currently have the throttle body out and seem to be pulling more bits out than putting back in at the moment but with the tb out it's a good time to work around the distributor etc.

I have one of those inline spark testers, if the results all look the same when it's running (has a transparent body with a lamp in it) would that be considered proof enough the cable and dist cap is ok? Keep in mind I have not found the definitive proof of what's causing the original issue (and I know if the cats are bad/fouled there has to be an initial cause anyway, only thing that's different is I had the injectors/fuel system cleaned a few months ago.

Any thoughts on this? Like I said, I'd like to replace and forget but I'm trying to target the dollars to the proven bad stuff, so far.

 

Guess I've answered part of my question, at least some of the other plug boots have a powdery residue in them, I'm thinking it's either remnants of a cheap dielectric grease I used (using a better one now) or perhaps residue from coolant, I had to replace an upper hose and coolant got spread around a bit...

Like I said, so far the plugs look pretty good so I'd assume there was good spark....with so much stuff removed now certainly would be the time to do all the plugs and wires but I don't see how they would cause a code "41 no hego switching detected" code. Depending on what people consider (please chip in) normal wear and tear and residue you'd expect to see on cables and a dist cap say 20-30,000kms old, I'll plan to replace them and try to clean them up in the meantime (is electrical contact cleaner safe in a plug boot?) unless there's some compelling evidence the plugs/cables/dist cap are the root cause of it....

Can a misfiring plug cause lean mixture? I'd assume it'd cause the oxygen sensor to assume rich, as it detects unburned fuel in the exhaust...also, I'd expect to see the plugs fouled as well.